Follow the author of this article

Follow the topics within this article

The Mona Lisa’s pallid complexion, thinning hair and possible neck goitre were a result of thyroid problems, a new study claims.

Scientists in the US believe that clinical hypothyroidism explains the yellowish skin and receding hairline of Leonardo da Vinci’s most famous portrait.

The woman in the world’s best-known painting is believed to be Lisa Gherardini, the young wife of a wealthy silk merchant in Florence.

Dr Mandeep Mehra, from Harvard Medical School in Boston, and Hilary Campbell from the University of California, Santa Barbara, dismiss the hypothesis of other scientists that Gherardini was suffering from heart disease or a lipid disorder.

Those conditions would have killed her at a young age, they suggest, whereas she lived to the relatively ripe old age of 63.

A more likely explanation is that she was suffering from clinical hypothyroidism, which would account for the “yellowish discolouration” of her skin, receding hairline and “complete lack of eyebrows”.

They also believe that Leonardo’s painting, which hangs in the Louvre in Paris, hints that she was suffering from a goitre – a swelling in the neck resulting from an enlarged thyroid gland.

“Curiously, a close look at the neck does insinuate the possible presence of a diffuse enlargement such as a goitre,” the researchers said.

“If Lisa Gherardini was indeed suffering from severe hypothyroidism or its consequences, the mysterious smile may at one level be representative of some psychomotor retardation and muscle weakness leading to a less than fully blossomed smile,” the researchers said in a report in the journal Mayo Clinic Proceedings.

The goitre could have been caused by a lack of iodine in the young woman’s diet.

People in Renaissance Italy ate plenty of root vegetables and cereals but little meat or seafood, the scholars suggest.

“The diet was one that was often iodine deficient and more importantly, the eating habits promoted the development of goitres,” they wrote.

Hypothyroidism can also be exacerbated by pregnancy and giving birth, and Gherardini had had a son, Andrea, months before sitting for the painting.

“We believe that the enigma of the Mona Lisa can be resolved by a simple medical diagnosis of a hypothyroidism-related illness that could have been the result of a peripartum thyroiditis (inflammation of the thyroid after pregnancy) accentuated by the living conditions of the Renaissance,” the researchers conclude.

But it is those medical conditions that make the portrait so interesting.

“In many ways, it is the allure of the imperfections of disease that give this masterpiece its mysterious reality and charm,” they said.

Leonardo was commissioned to paint Gherardini by her husband, successful silk merchant Francesco del Giocondo, in 1502, following the birth of their first child.

The Renaissance master used a technique known in Italian as “sfumato”, the blurring of lines by blending colours, which left the corners of Gherardini’s mouth and eyes in shadow, lending her an ambiguous expression.